“She is a tiny little girl so for her even taking her blood pressure was mayhem,” Yvette said.

“I was in absolute shock, when she started chemo it started to hit me hard.

“She’s been an inspiration,” Yvette added.

Keira is one of Cancer Research UK’s Little Stars and this year received an award for courage shown during cancer treatment.

Yvette, who has two other children, Chloe, five, and Jack, 18 months, said: “I never, never thought for one minute it would be cancer. To this day, I still can’t bring myself to call it cancer, I just say leukaemia.”

She lost her hair, suffered temperature spikes, and her Hickman line, a catheter used to deliver drugs, became infected and she was rushed to intensive care for three weeks. Following the transplant Keira was left with no immune system and had to spend three weeks in isolation to avoid infection.

Yvette said: “Before she was ill, she was quite a quiet, timid little girl. Not any more, now she has grown not only in size but in attitude.

“I think she knows far more than a three-year-old should. But that is because she has spent so much time around adults and she is familiar with all the medical terms used around her.”

Keira still goes for regular weekly checks at the Royal Marsden Hospital in Sutton.

Keira and her mum are also encouraging others to nominate children for a Little Star award, a partnership between Cancer Research UK and fashion retailer TK Maxx.

Visit cruk.org/littlestar to nominate.

Thanks to research and improved treatments, overall survival has doubled in the last 40 years and three-quarters of children with cancer are successfully cured compared to only a quarter in the early 1970s.